Invasive Species Management

“All living organisms co-exist with a predator, a marauder- a delimiter. Count your blessings, for then there are exotic species which have escaped their nemesis for an ignorant fancy, becoming a Trojan horse in a foreign land.” - Larry W. Richardson

Refuges strive for biological integrity, diversity and environmental health. Much of the management work of refuges is to maintain, enhance or restore intact and self-sustaining habitats. One of the refuge’s most important management responsibilities is to manage and control invasive species.

An invasive species is one that is not native to an ecosystem and which causes, or is likely to cause, economic or environmental harm or harm to human health. Invasive species are harmful to our natural resources (fish, wildlife, plants and overall ecosystem health) because they disrupt natural communities and ecological processes. This causes harm to the native species because they are forced to compete with a new species for the same resources (food, water, shelter, etc.). The invasive species typically outcompete the native species for food and habitats and sometimes even cause their extinction. Even if the native species are not completely eliminated, the ecosystem often becomes much less diverse. A less diverse ecosystem is more susceptible to further disturbances from diseases and natural disasters.

When an invasive species first becomes introduced into a new area, there may be a chance to eradicate it through a rapid response action if it is detected in time. If eradication is not possible, then the species may be subject to control and management efforts. Regardless of whether the goal is eradication or control/management, there are a suite of different options, which differ depending on the species, which one must consider. When making decisions on which options to use, the refuge uses an Integrated Pest Management approach to choose the options which will be the most environmentally sound yet still affect the invasive species as strongly as possible. The various options for eradication/control/management include:

Physical or Mechanical Control - This type of control involves physically removing the invasive species or using barriers or traps to prevent their spread or to capture them. For invasive plants, mowing or cutting is another example of physical control. This is the typical method for most invasive animals and for large monoculture stands of invasive plant species.

Chemical Control - This type of control involves all sorts of pesticides (herbicides, insecticides, fungicides, piscicides, etc.) Although chemical use can be very effective, they can be very dangerous to other species or to the ecosystem in general and must be used in an environmentally sound manner. The key is to choose chemicals that are low-risk yet effective and that can be applied when the pest is at its most vulnerable.

Biological Controls - Currently, there are no biological control efforts on the refuge. This type of control is the purposeful use of an invasive species’ enemies (predators, parasites, and pathogens) – in other words other exotic species – to reduce the invasive species populations. This option involves much research and testing to be sure the species to be used preys only on the target invasive species.